Automatic reclosing circuit interrupter



July 17, 1928. 1,677,328

C. A. BUTCHER AUTOMATIC RECLOSING CIRCUIT INTERRUPTER Filed April 25.1921 l as WITNESSES: F 3. INVENTOR ZJJWM l7 Cfmr'les/lfiufcher:

AIZTORNEY Patented July 17, 192

" UN TATES ATENT QFF'ICE.

cmmis a. BUTCHER, onmsr rnrcrsiaunqn, PENNSYLVANIA, QASS'IGNOR' :rownsrmenousn nnncrnrc & manurac'ruame conr'AnY, acoaroRA'rIoN or ammr-SYLVANIA,

- AU-romnrm ancnosrim cmcurr mrmmor'rna A Application filed 4 m '25,

. My. invention relates to circuit interrupters and particularly 'to'automat c clrcplt interrupters.

One object of my invention is to provide a circuit vinterrupter thatshall be automatically openedupon the occurrence of a short-circuit on acircuit to be protected thereby, and that shall be reclosed when theshort circuit is cleared or removed to render the protected circuit,normal.

Another object of my "invention isto provide a circuit interrupter for asystem, of the above indicated character, that shall be reclosed whenthe-short-c'ircuit conditions are cleared and when the efiective'connected load is at 'or below a predetermined value.

- A further object ofmy invention is to provide an -interrupter,.of theabove-indicated character, that shall be simple and economical initsconstruction and reliable in its operation. Y Q In systems heretoforeemployed for. controlling'trolley-feeder conductors, large re.-

sistors having'large current-carrying capace ity have been required. Insuch systems, upon the occurrence of-an extremely heavy overload orshort-circuit, the interrupter was opened to permit the insertion of aresistor or resistors of relatively lowresistance and having arelatively large current-carrying capacity to limit the current that,might 4 traverse the feeder conductor to a safe value. When theresistors were traversed by such A current for a predetermined intervalof time and heated to a predetermined unsafe temperature, the feedercircuit was entirelydisconnected from the source ofenergy until thefaultmightbe clearedand the resistors cooled. I i.

In Itie prior art, circuit breaker systems have resistor in series witha cont-rolling winding when the circuit interrupter is-openedif Thecurrent to the load circuit and fault traverse the resistor. and the"control winding and maintain an auxiliary reclosing circuitopen,

until the current traversing the resistordi-- minishes to apredetermined value. The control "winding is "then deenergizedjto asufiicient degree to permit the auxiliary reclosing-circuitto bereestablished and the interrupters-reclosed.

Since the-winding in such cases is traven provided which insert alimiting .1921. Serial Ho. 464,2 68.

ersed by the load and "circuit current under abnormal conditions,'it hadto bemade of large conductor of low resistance, and could not be made assensitiye as a potential winding which canbe madeofa small conductor ofhigh resistance.

By inserting the resistor directly inthe circuit, when the interrupteris opened and utilizing the potential thereacross, which can be measuredby a sensitive voltage coil, a greater sensitivity maybe obtained tocon.- 'trol therecl'osing of'the interrupter. I In- 'practijcingmy'invention, I provide means that'areenergized only upon theoccurrence-ot "a "sho'rt-cir'cuit upon the feeder circuit'to o'pen'theinterrupter to permitthe efi'ective insertion of areslstor of relativelyhigh resistance between the source of energy and the feeder-conductorcircuit. Upon the clearance of the'short-circuit and upon the increaseof'gthe effective-load resistance to or above'a' predetermined value,the interrupter is reclosed to shunt the limiting resis- 'tor; Since"the opening of the interrupter may be eifected' onlyby such currents asmight result a from short-circuit; conditions, the interrupter,""whe-nreclosed to connect a load of relatively low resistance to the maincircuit, is not-immediately reopened because of the sudden rush. of-current.

Figure lof the-accompanying drawings is a diagrammatic view of;anelectrical circuit including an "interrupter and a control systemembodying my invention; and

Fig.2 is a'diagrammatic view of a similar circuit including a modifiedcontrolling de- V1ce Referring to Fig. 1, a source 1 of directcurrentelectromotive iorce provides energy .for a supply circuit 2 "from whichenergy is supplied tofa" feeder circuit 3 through a circuit interrupter4.

' The interrupter 4 comprises a main switch 5, an auxiliaryswitchz6andan operating coil 7 that-serves to'closeboth switches, when energized;=The circuit of the .coil 74s completed through a switch 8 0i" "a" relay9 and a switch'10 of a relay= 11.

The relay 9 comprlse's the switch 8 and an operating'coil 12. Therelay11-comprises the switch 10, a floating lever arm '13 and twocontrolling coilsl t and 15, respectively. that control the switch .10.throughithe lever arm 13. The circuit of the operating coil 12 of therelay 9 includes the switch 10 and a resistor 16. i

v A current transformer 17 and two relays 18 and 19, respectively,areemployed to ef- -fect the actuation of the interrupter 4 to. open themain switch 5 upon the occurrence of a short-circuit on the feedercircuit- 3.

.The relay 18 comprises a switch 20 "and an actuating coil 21. The relay19 comprises a switch 22 and an actuating coil 23.

Upon the occurrence of a short-circuit that serves to efi'ect theopening of the interrupter -4, a resistor 24, that is connected acrossthe terminals of the switch 5, is inserted between the supply circuit 2and the .ffeeder circuit 3 to limit the current that may traverse thelatter circuit. -The actuating coil 14 of the relay 11 is connectedacross the terminals of the resistor 24.

.. While conditions are normal in the syscircuit 3, and consequently,the primary winding of the current transformer 17 suffices to quicklyenergize the winding of the relay 21 to effect the closing of the switch20.. -Upon the closing of the switch 20, a circuit is completed throughthe auxiliary switch 6, the switch 20 and the coil 23 of the relay 19that permits the energization of that coil to close the switch 22. Theswitch 22, when closed, completes a holding circuit for the coil 23through the auxiliary switch 6" until the interrupter 4 opens.

The moving members of the relays 18 and 19 are relatively lightin weightand rela tively sensitive. mentarily closed, short-circuits theoperating coil 12 of the relay 9. The immediate closing of the switch 22thereupon serves to maintain the short-circuit about the coil 12 of therelay 9, and the switch 8 is permitted to open. A 1

Upon the opening of the'switch 8 of the relay 9, the interrupter 4 isalso permitted to open, and the main switch 5 and the auxil-- iaryswitch '6 are opened. The opening of- .the auxiliary switch 6de-en'ergizes the coil 23 of the relay 19 to. permit the switch 22 toopen.

Upon the opening of the switch 5, the re sistor 24, which, for example,may have a resistance of ohms, is inserted 'into the feeder circuit tolimit the current that may The switch 20, when mo-' traverse the same toa maximum of 10 am-. -.peres, assuming that the voltage of the C11- cuit2 is normally 600 volts. When the shortcircuit conditions in the feeder.circuit 3 are cleared and the effective load resistance con-- nectedthereto equals or exceeds 0.6 of an ohm, the maximum current thatunjaytrav erse the interrupter. is 9.9 an'iperes.

Assuming short-circuit conditions on the circuit 3, the full voltage ofthe. circuit 2,.

normally 600 volts, will be consumed in the resistor 24 and,consequently, the corresponding potential difference thereacross will beeffective in energizing the coil 14 of the relay 11. Since the winding15 is correspondingly energized by a potential difference'of 600 volts,the relay 11 is maintained in a balanced position at whichposition theswitch 10 is maintained open.

However, when the short-circuit is cleared and the resistance of theconnecting load increases toor above 0.6 of an ol'nn, the potentialdifference across the terminals of the resistor 24 is 594.volts.

between the potentials applied to the two coils 14 and his thus 6 volts.Since the re lay 11 may be arranged to obtain'a sensitivity of 1%, thedifference in the degree of energization between the two coils 14 and15, effected by the difference of 6 volts, will suflice to effect theclosing of the switch 10. I V

. The closing of the switch 10 immediately completes the circuit of theoperating coil 12 of the relay-.9. whereupon the switch 8 is closed. Theclosing of the switch 8 completes the. circuit of the operating coil 7of the interrupter 4, and the main switch is thereupon reclosed.

\Vhen the switch 5 is closed and the resistance of the connected load is0.6of an ohm,

1000 amperes will immediately traverse the circuit. However, since tlnsvalue of cur,- rent is far below such value as might be causedtoitraversc the circuit by short-circuit conditions, the currenttransformer 17 is not sufiiciently energized to effect the actuation ofthe relays18 and 19.

The difference If, however. the magnetic circuit of the currenttransformer 17should not be magnetized, the sudden rush of'current ofsuch value might be sufficient to actuate the relays 18 and 19 toefl'ectthe opening of the main interrupter. Upon the occurrence of suchopening, "however, the. magnetic circuit would be so magnetized and.relatively so saturated that the consequent rush of curreng upon thenext reclosing would not again b sufficient to'effect the operation ofthe relays 18- and 19;

The feeder circuit- 3 may be connected directly, through a series ofsections connected N by sectionalizing switches, to a distant source ofenergy; but t 4, upon the occurrence of short-circuit and 'thereclosing, upon the clearance of the e opening of the interruptershort-circuit, at a predetermined value of load resistance, will beefiected irrespective of whether potential is applied to the circuit 3from an exterior source. 7

The operation of the system illustrated in Fig. 2 is similar to thatdescribed in connection with the system illustrated in Fig. 1

- with the exception of the relay 25 which 7 more, the coil 27 issufiiciently energized to maintain the switch open. When the po tentialdifference across the terminals of the resistor decreases to a valuebelow 594: volts by reason of an increase of the load resisttheaccompanying drawings, will thus dis connect a load circuit from asupply circuit upon the occurrence of short-circuit conditions in theload circuit and will immediately reconnect the load circuit when theshort-circuit conditions are. cleared and the connecting load of theload circuit is at or above a predetermined value.

My invention is not limited to-t-he specific devices illustrated or tothe specific arrangement of those devices, since modifications may bemade therein within 'the'spirit and scope of the invention, as set forthin the appended claims.

I claim as my invention 1. An automatically reclosingcircuitinterrupting device comprising means for connecting twoeircuitconductors, an operating coil therefor, a switch in circuit with thecoil, and means for controlling the switch comprising a resistorconnected directly across the terminals of the interrupting device andmeans responsive tov the potential difference thereacross when theswitch is open.

2. An automatically reclosing' interrupting device comprising means forconnecting two circuit conductors. and operating coil therefor, a switchin circuit' with the coil, and means for controlling the switchcomprising a resistor connected directly across the terminalsof theinterrupting device, means responsive to the potential circuitdifferencethereacross when the switch is open and means for controlling theeffectiveness of such potential difference.

3. In an electric system,.tl1ecombination with a supply circuit, a loadcircuit and a circuit interrupter therebetween, of a current-limitingresistor connected in parallelrelation to the circuit interrupter, meansfor opening the circuit interrupter in response to predeterminedabnormal conditions in the load circuit, and means for reclosing thecircuit interrupter when the resistance of the load circuit equals orexceeds a predetermined value, comprising a closing coil for the circuitinterrupter, a switch for controlling the energization of the closingcoil,

and two opposed coils for controlling the operation of the switch, oneof said coils being connected in parallel relation to the supply circuitand. the other ofsaid coils being connected in parallel relation to the1 current-limiting resistor.

4. In an electric system, the combination with-a supply circuit, a loadcircuitand a circuit-interrupter therebetween, of a current-limitingresistor connected in parallel relation to the circuit-interrupter,means for openinethe circuit interrupter in response to predeterminedabnormal conditions in the load circuit, and means for reclosing thecircuit interrupter when the resistance of the load circuit equals orexceeds a predetermined'value. comprising a closing coil for thecircuit-interrupter, a switch. for controlling the energization of theclosing coil, and two coils for controlling the operation of the switch,one of said coils being so disposed as to beresponsive to the potentialacross the supply circuit and to tend to close the switch. and the otherof said coils being so disposed as to be responsive to the potentialacross the current-limiting resistor and to tend to open the switch.

5. 'In an electric system, the combination with a supply circuit, a loadcircuit and an interrupter therehetween, of means 'for open- CHARLES A.BUTCHER.

